Melting intermetallics

Person 1 Determine the phases present, the relative amounts of each phase, and the composition of each phase when the only incongruently melting intermetallic compound in this system is heated to 800°C. 

Growth from melt e.g. congruently melting intermetallic compounds... 

It is important to understand the thermodynamic basis of the phase diagram to which an alloy belongs. A congruently melting intermetallic compound (e.g., UAlj in Fig. 1) may melt above or below the mp of its end members. A solid intermetallic phase... 

Betterton-Kroll process. A process for obtaining bismuth and purifying desilverized lead that contains bismuth. Metallic calcium or magnesium is added to the molten lead to cause formation of high-melting intermetallic compounds with bismuth. These separate as a surface scum and are skimmed off. The excess calcium and magnesium are removed from the lead by use of chlorine gas as mixed molten chlorides of lead or zinc. Bismuth of 99.995% purity is produced in this way. 

Table 6.7 is a data file for the modeling of the melting points of 1-1 type congruently melted intermetallic compounds between rare earth and... 

Reference has already been made to the high melting point, boiling point and strength of transition metals, and this has been attributed to high valency electron-atom ratios. Transition metals quite readily form alloys with each other, and with non-transition metals in some of these alloys, definite intermetallic compounds appear (for example CuZn, CoZn3, Cu3,Sng, Ag5Al3) and in these the formulae correspond to certain definite electron-atom ratios. 

Several Intermetallics, for example Ni3Al, are ordered right up to the melting temperature showing only minor variation of order parameter with temperature. In the present paper LRO-kinetics is studied in CusAu, where a Ti of about 390°C allows a considerable variation of the degree of LRO until its complete dissolution. We report on results of recrystallized material as well as samples deformed in the disordered and the ordered state. Part of this work was already presented at an earlier conference. ... 

The hot-dipped coatings are distinct from the others in having practical thickness limits and in possessing an inner layer of intermetallic compound, usually described as the alloy layer. The flow-melted electrodeposited coatings also have an alloy layer, which is somewhat thinner than that obtained in hot dipping. 

Another application of the electrolysis of tantalum and niobium in fluoride melts is in the preparation of intermetalic compounds as a result of the interaction between the electrochemically precipitating metal and the cathode material. Based on an investigation of the electrochemical reduction of K2TaF7 or K2NbF7 in a LiF - NaF melt on nickel cathodes, Taxil and Qiao [565] determined the appropriate conditions for the formation of TaNi3 or NbNi3 in the form of stable phases in the bulk of the obtained layer. 

Two phase diagrams are available for lithium-copper systems. No intermetallic phases were found, but LiCu4 was later observed. Substantial solid solubility of lithium in copper approaching 20 at% at the melting point of Li has been observed. 

Typically, Be-containing alloys and intermetallic phases have been prepared in beryllia or alumina crucibles Mg-containing products have been synthesized in graphite, magnesia or alumina crucibles. Alloys and compounds containing Ca, Sr and Ba have been synthesized in alumina , boron nitride, zircon, molybdenum, iron , or steel crucibles. Both zircon and molybdenum are satisfactory only for alloys with low group-IIA metal content and are replaced by boron nitride and iron, respectively, for group-IIA metal-rich systems . Crucibles are sealed in silica, quartz, iron or steel vessels, usually under either vacuum or purified inert cover gas in a few cases, the samples were melted under a halide flux . 

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